The memoirs of Janusz Meissner, the famous Polish pilot and writer, contain the following lines: “Some time ago the stench of castor oil began to drift through the air of the service hangar.

This was where repairs were made to a French SPAD-VII. Its 140-hp geared engine was lubricated by this rare substance, which made one think of a pharmacy. The aircraft was captured from the Austrians and was being restored to flying condition in Polish workshops. After repairs it was to be test-flown by a pilot who had won the Iron Cross while serving with a German fighter squadron. Curious how the fates of men and machines interweave sometimes in most unusual ways”

The author of the passage was recalling an event that occurred at Lewandówka airfield in Lvov. The name Spad was familiar to all pilots who participated in the Great War. It was closely related to the names of two distinguished aviation pioneers, Armand Deperdussin and Louis Blériot. Armand Deperdussin was fascinated with aviation. In 1911, in the town of Grenelle, he set up a company he named Société des Aéroplanes Deperdussin2. In 1912 the name changed to Société Provisoire des Aéroplanes Deperdussin (SPAD) and the company moved to Bois-Sulain. With the help of talented engineer Louis Béchereau, hired by Armand Deperdussin as technical director, the company produced a variety of successful aircraft designs. They were branded Deperdussin. Béchereau’s design team included André Herbemont and a Dutchman, Frederic Koolhoven. In summer 1913 Armand Deperdussin was arrested on charges of fraud and his company went bankrupt. In August 1914 the company’s assets were bought up by Louis Charles Joseph Blériot, with Béchereau and Herbemont as shareholders. The company was renamed as Societe Pour l’Aviation et ses Derivees (SPAD) and the acronym became the aircraft brand name.

Louis Béchereau’s designs

In the early stage of the war the main design effort focused on arming aircraft with a forward firing machine gun. An alternative to a gun firing through the propeller disc was sought. One such solution was to mount the engine aft of the cockpit in a so-called ‘pusher’ arrangement. Some “pushers”, like the French Farmans, Voisins or the British Airco DH.2 saw combat. The SPAD company took a different approach to the problem, designing a two-seat tractor biplane with the gunner/observer’s nacelle mounted ahead of the propeller. Construction details of this configuration were patented as Brevet d’Invention No. 498.338, with a supplementary 1’ere Addition No. 22.088 to the original patent submitted on 7th June 1915. Thus the Spad S.A1 was created, a biplane of wooden construction, powered by a 59 kW (80 hp) nine-cylinder, air-cooled Le Rhône 9C rotary engine. The fuselage ‘box’ was made of wooden framework and had a rectangular cross-section. The fuselage upper decking was profiled to have a rounded shape. The front section of the fuselage, which included the pilot’s cockpit, was covered with aluminum sheets and plywood, while the section aft of the pilot’s cockpit was covered with fabric. The engine cowling was also made of aluminum sheets. The tailfin and tailplanes were tapered, in a fashion applied to later SPADs3. The nacelle that housed the gunner/observer was of wooden construction. It was supported from below by wooden V-shaped struts and pivoted on lugs at the lower ends of the undercarriage legs.

The wings were of wooden construction, with two rectangular spars and slightly rounded tips. Cutouts were provided in the central leading edge of the upper and lower wings to make room for the propeller blades, while cutouts in the wings’ trailing edge mid-section offered the pilot better visibility over the top of the upper wing and below the aircraft. The wing bay construction used the company’s patented Brevet d’Invention No. 488.191 dated to 4th July 1915. It was designed to eliminate excessive vibration4 in the wing-bay bracing wires. It was discovered that vibrations were generated at the intersection points of the wires (which were steel cables). Hence, a set of interplane struts was fitted, the struts being interconnected fore and aft at their midpoints. An additional benefit of this solution was that it further strengthened the wing bays. The ailerons were attached to the upper wings only and were operated by a rod and bell crank system. Control rods ran from the base of the control column, through the lower wings to external bell cranks located at the base of the rear outboard interplane struts. The bell cranks were connected to vertical push rods, which ran along the rear interplane strut and linked to the actuating levers of the ailerons. The undercarriage comprised two main wheels and a tailskid.